1. Field of the Invention
The invention is concerned with an instrument panel or dashboard for a vehicle, comprised of a form stable plastic carrier, a cover layer, and optionally an interlayer of a foam material or the like, with at least one flap-like rupturable part for the airbag of an airbag module, wherein the flap-like rupturable part is defined by scorings or separation lines and a hinge area and is provided with a reinforcement. The invention is further concerned with a process for production of a plastic carrier for an instrument panel, of a vehicle which is reinforced in the area of one or more airbag flaps, and is produced using flowable or injection moldable plastic material and an injection mold die.
2. Description of the Related Art
It is well known to provide in instrument panels at least one cover through which an activated airbag can burst in an appropriate situation. U-shaped separation lines conventionally define a single flap, and H-shaped separation lines are used to define two flaps. The forces which occur during tearing open of the flaps are very large, so that in certain cases during the tearing open of the flaps from the carrier hard break-away pieces can splinter off, which form projectiles launched into the passenger cabin and represent a danger of injury to the passenger. In order to prevent the release of such broken pieces, it has already been proposed to reinforce the flaps or, as the case may be, the instrument panel. It has been proposed for example in DE-A-196 48 138 to glue a reinforcement fabric to both sides of the separation lines on the outer side of the carrier. As an alternative embodiment it has been proposed to provide a fabric or mesh material on the underside of the cover layer along both sides of the tear lines, embedded in the foam material layer provided below the cover layer. In this embodiment a splintering off and launching of broken fragments out of the carrier cannot be prevented. With respect thereto it would be more effective to position the reinforcing material on the outer side of the carrier. In the case of providing the reinforcement on the outer side of the carrier it can however occur, that as a result of the high forces which are associated with the release of the airbag and which are also necessary, the reinforcements can partially release so that their purpose is not, or is only insufficiently, accomplished.
This is the starting point of the present invention, which addresses the task of so reinforcing the instrument panel in the area of the flap-like rupturable part(s), that a release of carrier fragments is effectively prevented.
This task is inventively solved thereby, that the reinforcement is comprised of at least a perforated and flexible layer, which is permeated by the carrier material in such a manner, that the innermost carrier layer covers the reinforcement layer in the manner of a slight rise or elevation.
In accordance with the invention, the reinforcing material is selected as a material which is capable of being bonded to or embedded in the carrier material, and which by its structure as well as its bonding or embedding effectively prevents the release of carrier break pieces, which could otherwise occur during the opening of the flap(s).
The invention is also concerned with the task of developing a process for production of a carrier for an instrument panel, which makes it possible to effectively reinforce or strengthen the carrier in the area of the airbag flap(s) in simple manner.
As concerns the process for production of the carrier for the instrument panel, the set task is inventively solved thereby, xi that a structure comprised of shallow recesses is provided or integrated in the injection mold die, upon which at least a perforated or open-mesh and flexible layer is introduced for reinforcement prior to injection of the plastic for the carrier.
In this manner the plastic material penetrates through the reinforcing layer in the area of the mold recesses and forms on the inner side of what is subsequently the carrier a structure having a slight elevation, which structure covers over the reinforcing layer. Thereby the reinforcing material is embedded in the carrier material in such a manner that it cannot be released, and a splintering off of fractions of the carrier material is effectively prevented during: an opening of the flaps.
In a preferred embodiment of the invention the perforated or open-mesh flexible layer is a large mesh net or fabric. A net or woven fabric is particularly easy to manipulate in the manufacture of the carrier, is easy to produce in various designs or embodiments and is very effective.
The elevation in the carrier layer or as the case may be the shallow recess in the injection mold die is preferably so selected in its size or width, that its cross section is larger than each of the individual elementsxe2x80x94the surrounded perforation interspaces or mesh openingsxe2x80x94of the perforated layer or the net or fabric. Therewith it is insured, that the perforated layer or the net or fabric can be embedded without problem in the carrier layer.
The elevation or as the case may be recess should, also for the purposes of supporting a good embedding of the reinforcing material, be generally adapted to conform to the size of the structure of the reinforcing material or the perforations therein, and preferably have a similar pattern, in particular in the form of diamonds or quadrilaterals or even linked circles.
A good embedding of the perforated layer is also aided when it is introduced in such a manner, that the material connections between the perforations are at least largely oriented crosswise to the slight elevation of the carrier layer or, as the case may be, the recess of the injection mold die. In the case of a net or fabric it is particularly preferably the case that it is introduced in such a manner, that its threads or fibers run diagonal to the slight elevation or, as the case may be, recess.
The reinforcement preferably extends from connection points to connection points over the airbag deployment channel for connection with the instrument panel. In order to guarantee a good connection or bonding of this/these plastic part(s) by welding, welding ribs or beads are formed on the carrier, which on their lower side are provided with small ridges which form the welding points. The small ridges are in particular so designed, that they run in the longitudinal direction, or alternatively transverse to the longitudinal direction, of the welding ribs. The reinforcement embeds itself during the manufacture of the carrier below the small ridges, and the secure and permanent welding or fusion between the small ridges and the airbag deployment channel can occur.
For an optimal effect of the reinforcement layer it is advantageous when it extends over the one or more hinge area(s) of the flap-like rupturable part or parts, and preferably extends at least partially over the separation lines.
A particular inventive design of the carrier in the hinge area is also particularly advantageous. Namely, this is provided herein with a notch or groove, via which the strength of the instrument panel is weakened. This groove makes possible a substantially unimpeded opening movement of the flap-like tear-open part without unnecessary demands on the carrier material.
In order not to impede an opening of the flaps, it is further of advantage, when the perforated layer has a corrugated or wave-shape pivot part extending over the hinge area and unfoldable during the opening or unfolding of the hinges of the flap-like rupturable part. A further improvement is achieved when the pivot part is formed of multiple adjacent waves of the perforated layer.
According to a further variation of the invention the instrument panel for the vehicle includes a form-stable plastic carrier, a cover layer, and optionally a preferably foamed intermediate layer, with at least one flap-like separable tear-open part for the airbag of an airbag module, wherein the tear-open part is defined by score lines or separation lines and a hinge area, and is provided with a reinforcement, wherein the reinforcement is comprised of an at least a preferably lattice shaped perforated flexible reinforcement layer, which is permeated by or embedded in the material of the plastic carrier, wherein the plastic carrier preferably covers over the reinforcing layer in the form of a raised grid or lattice network.